958-93 Prevention of Mental Stress-induced Wall Motion Abnormalities by Nifedipine GITS and Atenolol Therapy

Abstract

Previous investigators have demonstrated that mental stress can induce myocardial ischemia in selected patients with coronary disease manifested by new wall motion abnormalities on radionuclide ventriculography. It is unknown whether such ischemia is due to coronary vasoconstriction or to increased myocardial O 2 demand. We studied the effect of nifedipine GITS and atenolol as single-agent therapy on mental stress-induced ischemia in a double-blind. placebo-controlled, three-way crossover trial in 16 patients with stable angina. Each patient received maximally tolerated doses of nifedipine (mean daily dose: 88 mg). atenolol (mean daily dose: 91 mg) or placebo during each of 3 4-week treatment phases. At the end of each phase, patients underwent a mental stress procedure (Stroop color word test, mental arithmetic, and stress interview) with skin conductance monitored to gauge physiologic arousal. Left ventricular wall motion was graded in each of 5 regions using a scale from 3 (normal) to -1 (dyskinesis), and by regional ejection fraction. The segment with the largest deterioration in wall motion during placebo therapy was determined, and the effects of nifedipine and atenolol on this segment were compared. Mental stress caused a significant increase in skin conductance levels, with peak values similar on each therapy. Therapy with either nifedipine or atenolol prevented a deterioration in wall motion score (-0.6 for placebo; 0.0 for nifedipine. 0.0 for atenolol, each p < 0.01 vs. placebo). while only nifedipine prevented a significant decrease in regional ejection fraction (-13.0% on placebo; -5.6% for atenolol, p = 0.08 vs. placebo; -1.9% on nifedipine, p = 0.01 vs placebo, p = 0.4 vs. atenolol). The rate pressure product (heart rate x systolic blood pressure. RPP) at peak mental stress (i.e., peak myocardial O 2 demand)was 15.792 on placebo, and was reduced only by atenolol (12,287, p = 0.001). but not by nifedipine (15,185, p = NS). Both nifedipine GITS and atenolol are effective at preventing mental stress-induced ischemic wall motion abnormalities. although the mechanisms may be different. Nifedipine improved reg’lonal wall motion without reducing RPP. and thus may have prevented mental stress-induced coronary vasoconstriction. Atenolol improved regional wall motion and reduced RPP. and thus may have been effective by reducing myocardial O 2 demand.